Lippia alba(Verbenaceae): A new tropical autopolyploid complex?

Abstract

• Premise of the study: Tropical regions have high species diversity, and polyploidization is a major mechanism of speciation in plants. However, few cases of natural polyploidy have been reported in tropical regions. Lippia alba, is a tropical, aromatic shrub with a wide distribution, extensive morphological plasticity, and several chemotypes. The species has long been recognized as a diploid with 2n = 30 chromosomes. Recently, two variations in chromosome number (2n = 60; 2n = 12-60) have been reported, suggesting the occurrence of polyploidy within the species.• Methods: Flow cytometry was used to investigate the genome size in 106 accessions from 14 Brazilian States. Conventional and molecular cytogenetic techniques and pollen viability analysis were employed to characterize each chromosome number observed.• Key results: The DNA 1C-value varied from 1.17 to 3.45 pg, showing a large variation in genome size. Five distinct chromosome numbers were observed (2n = 30, 38, 45, 60, 90); three are cytogenetically described here for the first time. The 5S rDNA signals varied proportionally according to each chromosome number, but 45S rDNA sites did not. High rates of meiotic irregularity were observed, mainly in cytotypes with higher chromosome numbers.• Conclusions: The data provide new support for the occurrence of a polyploid series in Lippia alba. We provide a hypothesis for how this complex may have arisen. Other cryptic polyploid complexes may remain undiscovered in tropical regions.

Distribution, karyomorphology, and morphology of Aspidistra subrotata (Asparagaceae) at different ploidy levels in limestone areas of Asia

“…Daqing (Figure 7); the same case occurs in Phu Luang WS, north-eastern Thailand (Phonsena and De Wilde 2010), but unfortunately, the chromosome number of Thai material is unknown. As many polyploid plants are reported to be similar to their diploid parents and hence morphologically cryptic (Tate et al 2005, Reis et al 2014, Azizi et al 2016), there is also tiny difference between diploids and tetraploids of Aspidistra subrotata . The tetraploid plants may be distinguished from the diploid plants by their rigid petioles as well as thick and deep green lamina.…”

Atividade antimicrobiana e potencial terapêutico do gênero Lippia sensu lato (Verbenaceae)

“…Lippia é considerado um dos principais gêneros da família Verbenaceae, com aproximadamente 200 espécies de ervas, arbustos e pequenas árvores, cujos maiores centros de dispersão se encontram nos países do Hemisfério Sul e em algumas regiões tropicais da América do Norte e Austrália (Reis et al 2014, Gomes et al 2011, Sena Filho et al 2006, Pascual et al 2001. No campo, esse gênero se destaca por sua aparência chamativa no período de floração e por seu aroma forte e geralmente agradável, característico de seu óleo essencial .…”

Genetic relationships and polyploid origins in the Lippia alba complex

“…Multiple polyploidization events have been documented in the angiosperm genus Lippia (Verbenaceae) (Viccini et al., ; Campos et al., ; Pierre et al., ), and at least one species, L. alba (Mill.) N.E.Brown, comprises a polyploid complex involving four ploidal levels (2 n = 30, 45, 60, and 90, representing 2 x , 3 x , 4 x , and 6 x , respectively) and one aneuploid (2 n = 38) (Reis et al., ). Clarifying the complex relationships between polyploid lineages and their diploid ancestors in species complexes such as L. alba is crucial for understanding the evolutionary consequences of polyploidization (Soltis et al., ).…”

“…Lippia alba not only exhibits polyploidy, but also has other features that make the species an important model for study. It possesses extensive phenotypic and chemical variation (Reis et al., ; Viccini et al., ; Timóteo et al., ) and is widely used in folk medicine (Hennebelle et al., ). Viccini et al.…”

“…Lippia alba is an aromatic shrub that occurs in a broad range of habitats, including forests, swamps, and fields, and is widely distributed throughout the Americas. Each ploidal level occupies a broad range of habitats from different parts of Brazil (Reis et al., ). The species is found in sandy soils and on the banks of rivers, ponds, and lakes, ranging from regions with a tropical to temperate climate (Moldenke, ).…”